The flexible flat cable (FFC) is a new type of data transmission cable and has the advantages of regular wire arrangement, high throughput, flat structure, small volume, easy detachment, and good flexibility, so that it can be easily and flexibly applied to various electronic devices. The FFC is particularly suitable for use under high-frequency and flexibility-demanding conditions, for example, as a connecting portion of a mobile element. The FFC can use a connector to perform an insert connection, or be directly soldered on a printed circuit board.
The FFC mainly includes a plurality of flat conductors that are arranged on a same plane and parallel to each other and an insulating layer laminated on the flat conductors. To avoid electromagnetic interference (EMI) and noise, a metal layer serving as a shielding layer is disposed on the periphery of the insulating layer and at least some of the flat conductors are electrically connected to the shielding layer to provide ground connections.
In the application of servers, with the diversification of server functions and the quickening of server computation abilities, there are higher requirements for internal jumpers, extension of signal transmission, and signal transmission between external machine groups. To increase the convenience of cable management, the FFC is often used for data transmission. However, the high-speed transmission characteristics of the conventional FFC are worse than that of the general high-speed transmission cable (e.g., a coaxial cable). In addition, when the conventional FFC extends beyond a certain length, crosstalk between transmission signals may be easily generated, and most solutions to such a problem cannot be adapted to automated mass production. For example, a large flat electrical cable disclosed in U.S. Pat. No. 5,250,127 requires that the line width and the line spacing of the transmission or ground wires cannot be too small, so that products cannot be effectively miniaturized.